Williamsport is a city in and the county seat of Lycoming County, Pennsylvania, United States. As of the 2020 census, it had a population of 27,754. It is the principal city of the Williamsport Metropolitan Statistical Area, which has a population of about 114,000. Williamsport is the larger principal city of the Williamsport-Lock Haven Combined Statistical Area, which includes Lycoming and Clinton counties.

The city is the cultural, financial, and commercial center of North Central Pennsylvania. It is 177 miles (285 km) from Philadelphia, 199 miles (320 km) from Pittsburgh and 85 miles (137 km) from Harrisburg. It is known for its sports, arts scene and food. Williamsport was settled by Americans in the late 18th century, and began to prosper due to its lumber industry. In 1930, the city's population reached a high of 45,729 but since the Great Depression it has declined by approximately 40 percent to 27,754 in 2020.

As county seat, Williamsport has the county courthouse, county prison, sheriff's office headquarters and federal courthouse, all downtown. It is also home to two institutions of higher learning, the Pennsylvania College of Technology, also known as Penn College, and Lycoming College. Williamsport is the birthplace of Little League Baseball. South Williamsport, a town across the West Branch Susquehanna River, is the headquarters of Little League Baseball and annually hosts the Little League World Series in late summer. Other points of interest include the Hiawatha riverboat, Millionaires' Row, Peter J. McGovern Little League Museum, the Community Arts Center, the Genetti Hotel, the Susquehanna Riverwalk, and The Gallery at Penn College.

Williamsport is located 129.2 miles (207.9 km) northwest of Allentown and 86.3 miles (138.9 km) north of Harrisburg.

In 1763, the Battle of Muncy Hills took place during the French and Indian War. It was a clash between the Native Americans and colonists seeking homestead sites in Native American territory. In 1768, at the Treaty of Fort Stanwix, the British purchased the land that became Lycoming County from the Iroquois Nation who controlled the lands.

In March 1796 the first house was built in Williamsport. James Russell built his inn on what is now the northeastern corner of East Third and Mulberry Streets in downtown. On April 13, 1795, Lycoming County was formed from Northumberland County. It encompassed all the lands of Northumberland County situated west of Muncy Hills and was a domain of 12,500 square miles (32,000 km²), comprising most of north central Pennsylvania. In 1796 the first recorded childbirth in Williamsport was James Russell, the son of Mr. and Mrs. William Russell and grandson of James Russell of the Russell Inn, and the first school was built as a one-room log addition to the building that would eventually become the first Lycoming County Courthouse. In 1798 the first brick house in Williamsport was erected on Front Street, between Market and Mulberry, by Andrew Tulloh, a lawyer. The bricks were made on the banks of Grafius Run where that stream crossed Hepburn Street.

In 1799, a post office opened at the corner of Third and State Streets in what is now downtown, and the following year, a jail was constructed at the northeast corner of William and Third Streets. The post office was later converted to a saloon.

In 1801, the town's first store was opened by William Winter on Third Street. In 1831 Jacob L. Mussina established the Repasz Band, the oldest brass band in America still in existence. On Oct. 15 1834 The West Branch Canal opened and the first boat to pass through the canal en route to Jersey Shore was that of George Aughenbaugh. The first freight carried into town was iron for the foundry of John B. Hall. The same year the enactment of the common school law by Pennsylvania Legislature led to public education here. In May 1835, the first public schools opened in Williamsport and also the town's first bank, the West Branch National Bank.